Currently, in view of global warming prevention, introduction of renewable energy power generation systems is in progress in the global scale. A wind power generation system is one of the renewable energy power generation systems that are being popularized, and performs power generation using wind power energy. However, in Japan, the popularization rate of the wind power generation system is low as compared to that in Europe or the like.
The reason for the low popularization rate of the wind power generation system in Japan is largely because of its geographical constraints. In Japan, wind force change and wind direction change are large due to the mountain climate, thereby making it difficult to stably maintain outputs in wind power generation. Such factors cause decrease in power generation efficiency per windmill, and consequently raise introduction costs of the wind power generation system.
In order to introduce a large-scale wind power generation system in a region where wind speed and wind direction change rapidly like in Japan, the above-described problems need to be overcome. That is, it becomes necessary to develop windmills that are variation resistant. Accordingly, in order to deal with the wind speed and wind direction changes, it is proposed that an airflow generation device to generate a plasma induced flow (airflow) should be disposed on a blade surface of a windmill. The airflow generation device includes a dielectric provided between a pair of electrodes, and applying a voltage between the pair of electrodes makes the airflow generation device generate the plasma induced flow.
In the wind power generation system, in addition to the airflow generation device, electric devices such as a heating device and an acoustic generation device are sometimes installed at the blade of the windmill. The heating device is installed at the blade of the windmill in order to melt ice adhering to the blade, for example. Further, the acoustic generation device is installed at the blade of the windmill in order to suppress vibrations, for example.
The wind power generation system is high in height, and therefore the blade and the like of the windmill are frequently struck by lightning. Therefore, when lightning strikes, there is sometimes a case that a current of lightning (surge current) flows into the electric device installed at the blade and the electric device is damaged. When the airflow generation device is installed at the blade, for example, a current of lightning flows into the electrodes formed of a metal material in the airflow generation device, and thereby the electrodes are damaged. Further, by a current of lightning, a power supply electrically connected to the electrodes of the airflow generation device is sometimes damaged. Additionally, there is a possibility that a portion near the position where the airflow generation device is installed at the blade is damaged by a current of lightning. Here, as the current of lightning, not only a current by a direct lightning strike, meaning that lightning directly strikes the electric device, but also a current by induced lightning to flow into the electric device by electromagnetic induction when lightning directly strikes a portion other than the electric device, for example, a lightning receiving part provided at the blade, a tower, or the like is included.
Therefore, in the wind power generation system, it is necessary to accurately protect the electric device and the like installed at the blade from lightning strikes. That is, it is necessary to prepare highly reliable measures against lightning.
Thus, a problem to be solved by the present invention is to provide a wind power generation system capable of accurately protecting electric devices and the like installed at a blade from lightning strikes and capable of improving safety.